diff --git a/core/modules/system/lib/Drupal/system/Tests/Theme/ThemeTest.php b/core/modules/system/lib/Drupal/system/Tests/Theme/ThemeTest.php
index f10d83d..e83f6aa 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Theme/ThemeTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Theme/ThemeTest.php
@@ -46,14 +46,16 @@ function setUp() {
    *   - any attributes set in the template's preprocessing function
    */
   function testAttributeMerging() {
-    $output = theme('theme_test_render_element', array(
+    $theme_test_render_element = array(
+      '#theme' => 'theme_test_render_element',
       'elements' => array(
         '#attributes' => array('data-foo' => 'bar'),
       ),
       'attributes' => array(
         'id' => 'bazinga',
       ),
-    ));
+    );
+    $output = drupal_render($theme_test_render_element);
     $this->assertIdentical($output, '<div id="bazinga" data-foo="bar" data-variables-are-preprocessed></div>' . "\n");
   }